Portable terminals are being developed in various forms such as Smart Phones, and Tablet PCs, and providing a variety of functions for users, thereby becoming more common in use.
As the portable terminals provide various functions as mentioned above, peripheral devices included in the portable terminals are gradually increasing in number.
For example, a flash LED along with a camera is included in the portable terminals, and a vibration motor is also included in the portable terminal due to addition of a vibration mode.
Such a peripheral device as described above may be controlled through General Purpose I/O pins (GPIO). The peripheral devices electrically connected to the GPIO are activated by rising edges or high signals, and deactivated by falling edges or low signals.
Meanwhile, various types of processor (for example, Application Processor, or Central Processing Unit) are employed in the portable terminals according to types of portable terminal.
However, when a battery is inserted into the portable terminal, or a power-on button is input to the portable terminal, the above-mentioned peripheral devices may malfunction due to combinations of specific processors.
For example, when the battery is inserted into the portable terminal, or a power-on button is input to the portable terminal in a power-off state, unspecified high signals are generated in the processors, and the peripheral devices connected to the processors through GPIO ports are unintentionally driven by the generated high signals.
The reason of such a malfunction as described above is because processors are not capable of normally controlling, the peripheral devices of the portable terminal, when the battery is inserted into the portable terminal, or before the portable terminal is completely booted after the input of the power-on button.
Accordingly, it is necessary to solve the problem where the peripheral device malfunctions irrespective of the control of the processor before the portable terminal is completely booted.